1. Field of the Invention
This invention relates to a frictionally sliding structure well-suited for a rocker arm, push rod, tappet, and valve bridge, each of which constitutes a dynamic valve system in an internal combustion engine.
2. Description of Prior Art
In an internal combustion engine, friction-resistant properties have been demanded in a dynamic valve system in order to comply with an improved efficiency and an adoption of EGR (Exhaust Gas Recycling Device).
It has been suggested that a friction-resistant ceramic material would be applied to frictionally sliding members which constitutes the dynamic valve system in the internal combustion engine.
When making a rocker arm for example, a ceramic chip is discretely brazed merely to a sliding surface of the rocker arm on which a cam frictionally slides. However, it is feared that the rocker arm may be thermally deteriorated due to the fact that the rocker arm is annealed under the influence of the brazing procedure so as to lose its required strength. In order to avoid the thermal deterioration, it is necessary to apply a specific alloy to the rocker arm, thus making a manufacuturer disadvantageous in cost.
According to another suggestion, the ceramic chip is integrally embedded into the rocker arm simultaneously when the arm is cast. However, it is feared that the ceramic chip would fall off the rocker arm with the passage of time due to thermal expansional differences between the ceramic chip and the rocker arm.
Therefore, it is an object of the invention to eliminate all the above drawbacks, by providing a frictionally sliding structure which is capable of preventing a sliding member from being thermally deteriorated without using a specific alloy when a ceramic chip is secured to the sliding member by means of brazing.